U horticulture educator Terry Nennich explaining the benefits of high tunnels or hoop houses at the University's North Central Research and Outreach Center in Grand Rapids, Minnesota. (The group is gathered in front of a high tunnel example.)

High tunnel craze

University of Minnesota Extension is working to improve Minnesota's fruit and vegetable production

October 30, 2007

Terry Nennich knew he was onto something as he trekked through
the lush flatlands of Normandy, France, in the summer of 1999. The
University of Minnesota Extension educator from Crookston had come
to study fruit and vegetable practices and stumbled upon
horticulture's version of a French revolution. The region's
miniature, greenhouselike huts--known as high tunnels--blanketed
the countryside. Inside, the plants were thriving; the cool spring
weather wasn't an issue. A light bulb went on for Nennich,
comparing everything he saw to his home climate. One might say his
French discovery kickstarted the high tunnel phenomenon in
Minnesota.

High tunnels, also called high hoops or hoop houses, are
temporary structures that extend the growing season. The
plastic-covered garden structures allow growers to roll sidewalls
up and down for ventilation and frost protection. Because the
system is enclosed, no rainfall enters the tunnel. Growers place
plants directly into the soil and water them with small irrigation
tubes under the plastic.

Nennich saw how enthusiastic the French were about this growing
system. Fruit and vegetable growers now had a longer growing
season; yields were two to three times the size of conventional
gardens; and consumer demand for these homegrown goods, a month
earlier than usual, added extra clout to what growers could charge.
In addition, the protective walls greatly reduced the need for
pesticides, or eliminated the need altogether, and new and
different crops could be added to the mix.

"If it weren't for Terry, we would not have been able to do
this," says Eldon Voigt, who, along with his wife, Melissa, grows
blueberries, onions, cucumbers, tomatoes and peppers on the
couple's farm, Elm Tree Fruit Farm, LLC, in International
Falls.

In 2004, Voigt, a pioneer from the "Icebox of the Nation," first
worked with Nennich to learn how to grow tomatoes in high tunnels.
Today, Voigt sells at a roadside stand and to a local deli.
However, he is most enthusiastic about a new project he and his
neighbors have organized.

On-farm research provides key to
growers' success

Dallas and Mary Flynn of Frazee monitor a high tunnel and
participate in the U's on-farm research. In exchange, the
University monitors the tomatoes and cucumbers grown in their
tunnel, analyzing plant tissue, as well as soil composition,
moisture and temperature.

Due to the high yields in tunnels, soil is depleted of nutrients
much more rapidly and in higher quantity than in field-grown crops.
Extension soil scientist Carl Rosen and his group analyze data,
such as how much nitrogen and potassium is taken up in the fruit.
They also study the benefits of adding soil amendments such as
compost before planting begins.

"We're trying to develop a nutrient budget," he says. "Things are
really progressing. The growers just have so much more confidence
in knowing how to manage the crop."

For the Flynns, the biggest challenge has been explaining their
growing system to customers. "I bring pictures with me every year
because I get the same questions, 'Who do you buy your cucumbers
from?'" says Dallas Flynn, who sits on the board of directors for
the Minnesota Farmers' Market Association. "The beauty of it is
when they find out it's locally produced by me. They love
that."

"We've started a community farmers' market with 10 vendors,"
says Voigt. In late June, their community market officially opened,
selling locally produced goods Saturday mornings in the lots
outside Backus Community Center in International Falls.

High tunnels didn't spring up in Minnesota overnight. Three
years of collaborative research by Nennich, Extension soil
scientist Carl Rosen, engineer Jerry Wright, and retired research
horticulturist Dave Wildung, as well as on-farm research, helped
lay a solid foundation. Then in 2004, Nennich and coauthors
finished the
University's manual on growing in high tunnels. There are an
estimated 150 high tunnels in use throughout the state, according
to the group.